There is an electric power steering system in the related art including an electric motor that outputs an auxiliary torque to a steering wheel of a vehicle and a control device that drives the electric motor under control, which are installed in the form of an electric driving device by attaching the control device to the electric motor.
For example, Patent Document 1 discloses an electric power steering system incorporating an electric driving device formed of a control device disposed on an axial line of a rotor shaft of an electric motor and fixed to the electric motor. Also, Patent Document 2 discloses an electric power steering system in which a control device is fixed onto a bracket of an electric motor and a housing of the control device and a cover of the housing are attached parallel to an axial direction of the electric motor.
In the electric driving device disclosed in Patent Document 1 or Patent Document 2, the control device is disposed on the axis line of the rotor shaft of the electric motor or on the bracket of the electric motor and fixed to the electric motor. Power boards are integrated into a single board and electrolytic capacitors are gathered at one point.
Also, the electric driving device as above is configured in such a manner that heat from a coil or electrolytic capacitors, which are heating components, is released into a space within an electronic control unit (hereinafter, abbreviated to ECU). Further, the electric driving device as above is configured in such a manner that a power portion and a control portion are connected by disposing terminals in a row and heat is released by providing a heat sink to the ECU or a motor case.
Also, in the electric driving device disclosed in Patent Document 2, a power line is formed of bus bars and a structure is formed by resin molding.